Electric-blasting-cap protector.



F. ALEXANDER.

ELECTRIC BLASTING CAP PROTECTOR.

APPLICATION FILED IUNE29, I96.

Patented Mar. 6, 1.917,

ATTI/5.

p FORD ALEXANDER, 0F TAFT, CALIFORNIA.r

ELECTRIC-BLASTING-CAP PROTECTOR.

Specication of Letters Patent.

Patented Mar. 6, 1917.

Application led June 29, 1916. Serial N o. 106,633.

To all 'whom z't, may concern: Be it known that I, FORD ALEXANDER, a citizen of the United States, residing at Taft, in the county of Kern and State of, California, have invented new and useful Improvements in Electric-Blasting-Cap Protectors, of which the following is a specification.

This invention relates to a' blast cap protector and detonating controller; and particularly pertains to an electrically ignited water proof concussion cap for use in deep well blasting.

It is common practice in the course of drilling deep wells whether they be of oil, gas or water, to explode nitroglycerin or other highly explosive compounds at the bottom of the well to increase the iiow of the well. It has been a comparatively simple matter to explode such charges in wells which are empty, but it has been difficult to operate in well shafts partly filled with liquid. This is due to the fact that weights which are ordinarily droppedr down a casing are robbed of their force when they strike the liquid and will not hit the explosive with enough power to set ito".

The principal object of'this invention is to provide an explosive cap particularly adapted for use beneath surface of a body of' water and which will be impervious to moisture .and readily ex loded.

Another object o this invention is to rovide a cap which is not liable to exp ode prematurely due to external pressure upon the shell which would cause its collapse.

Another object is to provide a cap of the class named which will be.k electrically ignited in a simple and certain manner.

'A further object is to provide a water proof detonatingcap which is simple in its construction and which may be {inexpensively manufactured. .1

c Other objects will appear hereinafter.

The 'invention is illustrated in the accompanying drawings in which:

Figure 1 is a View of a well casing invertical section with portions of its length broken away and illustrates theapplication and use of the water proof detonating caps wlth a. ca n of nitroglycerin.

4F 1g. 2 1s a view in elevation showing the cap in detail and particularly illustrating the manner in which its outer'fsurfa'ce is water-proofed.

Fig.v 3 is a view in vertical section as seen on .the line 3-3 of Fig. 2- and shows the interior construction of the cap as well as the manner in which the. explosive charge Iis ignited.

Referring to the drawings more particularly, 10 indicates a well casing which is l driven into the ground and here shown as being partly filled With water. The lower end of the casing terminates adjacent the bottom of a wellf shaft and it is the object of this invention to provide means .which may be used with safety and suretycto loosen the earth adjacent the end'of the well casing so that it may be further driven. As shown in the drawings, this. is accomplished by placing a container 11 of high p'owerexplosive at the bottom of the casing and setting it ofi"` by the shock produced by detonating caps 12 which are preferably positioned one above andthe other beneath the container. The essence of the present invention resides in the construction of these caps.

The caps 12 are lformed with cylindrical p body portions 14 which may be made of any suitable material but are preferably formed of cast iron or glass. The body portion 14: of each cap is tapered at its lower end to allow it to pass downwardly through the water with slight resistance and has an electrical conduit opening 15 formed' in the lower tapered end and in communication with an explosive chamber 16. The explosive chamberl is adapted to receive an explosive cap 1`6which is'formed with a thin metallic shell and is preferably filled with fulminate of mercury. The chamber .16 extends longitudinally of the body 14 and communicates with an enlarged longitudi-- nally extendin bore 17 which is providedfor the reception of an explosive capA 17 similar in construction to the cap 16. The bore 17 terminates within an enlarged chamis considerably longer than the plug and thus provides a chamber 20 Vfor a purpose which will hereafter bej disclosed.

In order to water-proof the cap or body member 14, the chambers 16, 17 and 18 are treated with shellac prior to charging them with their explosive char s. After being charged, 'the chamber 20 is filled with shellac and pressedupon the charge byv the plug 19. When the device has been assembled, the outer surface of the body portion is treated with fshellac and water-proof tape 21 wrapped thereupon. This ta e is afterward covered with shellac an the device is thus made thoroughly water-proof.

As a means for igniting the charge within -th'e cap, a pair of electrical conductors 22 and 23 are led through the opening 15 into the chamber 16 and through the lower end of the cap 16.v To properly seal the cap at the point where the conductor passes through and to insure the explosion 0f the charge within the cap', the conductors are surrounded at their point of entrance with plugs ofsulfur which are fusible as 'well as dielectric. 'The intervening space between the plugs is bridged .by a platinum wire 24 which communicates betweenfl the conductors 22 and 23 and generates sulficient heat when chargedwith electricity to.

set 0E the fulminate. n

In the manufacture of the cap, the body portion, which ,has been previously treated with shellac as described, is fitted .with the explosive caps 16 and 17. The cap l16 is wired as described 'and the wires are adapted -to be led to a battery 26 which is controlled by a switch 27. It may be here noted that the wall of the body portion 14 is of suiicientstrngth toi prevent the collapse of the'cap under pressure and yetis fragile enough to disintegrate when tl'fe charge explodes. When the explosive` caps are in place within the "body, a quantity of shellac is placed over the upper cap `and.

pressed downwardly by the plug 19, afte'r which the device is treatedfwith shellac and wrapped with the tape 21, which is subse- (luently shellacked. The cap is now ready or use and may be placed within any conned position and at the Vrexact point at which an explosion is desired without dan,- ger of premature i i-tion. When the cap is so placed, the fulminate may be instantly exploded by passing a current of electricity through the conductors 22 and.23 and the platinum wire 24. The heat generated by the current vpassing through the' platinum wire is sufficient to ex lode the Vfulminate in the cap 16 and th1s will subsequently" explode the larger cap 17. The concussion of these explosions 4is suliicient to cause the explosion of `the nitro-glycerin adjacent which the explosive member 14 is positioned.

It will thus be seen that I have provided a ldetonating cap which is impervious to moisture, will not readily collapse under external pressure, and which may besafely handled a'nd ignited to setof av charge of high power explosive iby its concussion.

1.'A detonating cap comprising a cylindrical body member of fragile material and having a pointed end, said member having a relatively small initial explosive chamber and a vrelatively large explosive chamber connected therewith, the walls of said chambers being coated with a water-proof layer, ascrew plug closing said large chamber, a water-proof layer inclosing said bodymember, a water-proof wrapping incasing the said member, a second. water-proof layer on the exterior of said-wrapping, and electrically operated means for exploding the charge in said small chamber.

2.`A detonating cap comprising a cylindrical body member of fragile material having a. relatively small initial explosive cham-y ber and a relatively -large explosive chamber connected therewith,- the walls of said chambers being coated with a water-proof composition, a plu closing saidlarge chamber, a water-proof abric forming a case for said member, said casing having a coating of water-proof varnish, and electrically operated means for explodingthe charge in said small chamber.

3. A detonating cap comprisin a onepiece lcylindrical fragile shell mem er, said member havin a tapered end and a pair of connected exp osion chambers of different diameters in longitudinal alinement and axially disposed in said shell member, the smaller chamber being adjacent to the tapered end of` said shell member, the larger` chamberhaving its outer end open,'whereby 'both chambers may be filled with explosive charges, a screw plug closing said open end of said lar er chamber, meansfor initially exploding t e charge in said smaller chamber7 and a. water-tight covering incasing said shell member.

4. A detonating cap comprising a onepiece cylindricalvfragile shell member having a pair of connected explosion chambers of different diameters in longitudinal alinement axially disposed insaid shell member, one ofsaid chambers opening to the end of said shell'member, a plug closing said open end of said chamber, means for initially 'exploding the charge insaid smaller chamber, and a water-tight covering incasing said shell member. v l y 5. A detonating cap comprising a cylindrical. body member of fragile material and having a longitudinal explosive chamber therefor, said casing being provided with a Water-proof coating on its exterior,v and electrially operated means for exploding the Charge in said chamber.

In testimony whereof I have signed my name to this specification.

FORD ALEXANDER. 

